My 2004 Endeavor did not have a trailer brake wire in the rear plug. There were 6 wires; left/right turn signals, ground, brake light, reverse light, and power. No brake wire. I had to run one from one end to the other. That is quite a task. On my old Tiffin gas burner I was able to run inside the frame, but on these it is impossible to do so due to the construction of the bottom storage. I was able to run a wire along the passenger side engine, to the LP gas area, crossed to the left side at the water/sewer area, then along the upper inside edge of the storage, thru the upper fuel door area, then back toward the center along other harnesses and then thru the front fire wall. Picked up power and the signal from the brake light relay in the lower power panel and ran in the firewall with the brake wire. Seems to work fine after that ordeal.